G98 and G99
/ jee ninety-eight and jee ninety-nine /
Also known as: G98, G99, DNO notification, grid connection
Definition
G98 and G99 are the engineering recommendations that govern connecting small-scale generation, such as solar PV and batteries, to the UK electricity network. G98 covers small systems that are notified to the distribution network operator (DNO). G99 covers larger systems that need DNO approval before they are installed.
In practice
As a general guide, systems up to 16 amps per phase, about 3.68kW on a single-phase supply, are notified under G98, normally within 28 days of commissioning. Larger systems need approval under G99 before installation, which can take longer and sometimes involves a network study or export limits.
Adding an AC-coupled battery to an existing system can push the total over the G98 limit, so tell your installer if a battery is planned. Your installer should handle the notification or application, and you should receive a copy for your records.
Building Regulations
Thresholds and processes are set by the engineering recommendations and each DNO. Check the current version and your DNO before relying on these figures.
Full guide: Solar PV for UK homesSee also